This application claims benefit of Japanese Application No. 2000-076790 filed in Japan on Mar. 17, 2000, the contents of which are incorporated by this reference.
1. Field of the Invention
The present invention relates to a multi-display device in which partial images projected from a plurality of image projecting means are arranged to construct one image as a whole, and a multi-display system.
2. Description of the Related Art
Various types of multi-display devices that use a plurality of image display devices serving as image projecting means to display one image have been proposed in the past. For example, Japanese Unexamined Patent Publications Nos. 5-103286, 3-53288, 9-211386, and 6-169444 describe such multi-display devices.
In the conventional multi-display devices, images projected from the plurality of image display devices overlap to have their edges superposed on adjoining edges in shared fields on a screen (see FIG. 1 concerned with an embodiment of the present invention). A sheet interceptor for intercepting light from the edge of a range on the screen within which a projector project an image is interposed between the image display device (projector) and the screen, whereby an amount of light is decreased for fear the luminance levels in the shared fields may get higher.
However, according to the aforesaid prior arts, there is difficulty in arranging sheet interceptors so that they can intercept light rays, which overlap and are projected from the plurality of image display devices, by an equal amount. Even if the sheet interceptors are aligned once in the course of manufacturing, when a lamp must be replaced with a new one thereafter, the image display devices may be moved or dismounted from the multi-display device. In this case, the positional relationships of the sheet interceptors to the image display devices must be adjusted again. This poses a problem in that the adjustment is time-consuming.
Moreover, as shown in FIG. 14, when images are projected from a plurality of projectors 1 and 2 so that the ray axes of light representing the images will be perpendicular to the major surface of a screen 10, the directivity of light reaching a shared field on the screen, in which the edges of partial images projected from the projectors 1 and 2 are superposed on each other is different between light projected from the projector 1 and light projected from the projector 2.
When such light is diffused on the diffusing surface of the screen (see FIG. 14 showing diffused light at point A and diffused light at point B), light diffused in the same direction as incident light is the largest amount of light. The amount of diffused light decreases with an increase in its angle with respect to the direction of incidence. An observer looking at the screen from a point in front of the screen will not sense that the luminance of the image becomes unnaturally discontinuous in the shared field on the screen. However, an observer looking at the screen from a point oblique to the screen will sense that the amount of light projected from the projector 2 is smaller than that projected from the projector 1, and that the luminance of the image becomes unnaturally discontinuous in the shared field.
Accordingly, an object of the present invention is to provide a multi-display device making it possible to observe an image, which consists of a plurality of partial images, with an almost equal luminance level over a screen including shared fields, and a multi-display system.
Briefly, according to the present invention, there is provided a multi-display device including a plurality of image projecting means and a light level adjusting means. The plurality of image projecting means projects partial images on a screen so as to construct one image as a whole. The partial images overlap to have the edges thereof superposed on edges of adjoining partial images in shared fields on the screen. The light level adjusting means adjusts an amount of light to be projected on the shared fields so that the luminance levels in the shared fields will substantially agree with the luminance levels in the other fields except the shared fields. The light level adjusting means displaces a light level adjustment range within which an amount of light representing one edge of a partial image to be projected is adjusted relative to an amount of light representing the other edge of the partial image.
According to the present invention, there is provided a multi-display system including a multi-display device, an imaging means, a luminance detecting means, a magnitude-of-displacement calculating means, and a control means. The multi-display device includes a plurality of image projecting means and a light level adjusting means. The plurality of image projecting means projects partial images on a screen so as to construct one image as a whole. The partial images overlap to have the edges thereof superposed on edges of adjoining partial images in shared fields on the screen. The light level adjusting means adjusts an amount of light to be projected on the shared fields so that the luminance levels in the shared fields will substantially agree with the luminance levels in the other fields except the shared fields. The light level adjusting means displaces a light level adjustment range within which an amount of light representing one edge of a partial image to be projected is adjusted relative to an amount of light representing the other edge of the partial image. The imaging means picks up the image displayed on the screen of the multi-display device. The luminance detecting means samples a luminance signal from an image signal output from the imaging means, and detects the sizes of the shared fields and the luminance levels in the shared fields. The magnitude-of-displacement calculating means calculates a magnitude of displacement, by which the light level adjusting means should displace the light level adjustment range, according to an output of the luminance detecting means. The control means extends control so that the light level adjusting means can displace the light level adjustment range by the magnitude of displacement calculated by the magnitude-of-displacement calculating means.
Furthermore, according to the present invention, there is provided an adjusting method for a multi-display device that includes a plurality of image projecting means and a light level adjusting means. The plurality of image projecting means project partial images on a screen so as to construct one image as a whole. The projected partial images overlap to have the edges thereof superposed on edges of adjoining partial images in shared fields on the screen. The light level adjusting means adjusts an amount of light to be projected on the shared fields so that the luminance levels in the shared fields will substantially agree with the luminance levels in fields other than the shared fields. The light level adjusting means displaces a light level adjustment range within which an amount of light representing one edge of a partial image is adjusted relative to an amount of light representing the other edge thereof. The adjusting method comprises an outputting step, a detecting step, a calculating step, and a control step. At the outputting step, the image displayed on the screen of the multi-display device is picked up in order to produce an image signal. At the detecting step, a luminance signal is sampled from the image signal in order to detect the sizes of the shared fields and the luminance levels in the shared fields. At the calculating step, a magnitude of displacement by which the light level adjusting means included in the multi-display device should displace the light level adjustment range is calculated based on the detected information of the sizes of the shared fields and luminance levels therein. At the control step, control is extended so that the light level adjusting means can displace the light level adjustment range by the magnitude of displacement. image projecting means projects partial images on a screen so as to construct one image as a whole. The projected partial images overlap to have the edges thereof superposed on edges of adjoining partial images in shared fields on the screen. The light level adjusting means adjusts an amount of light to be projected on the shared fields so that the luminance levels in the shared fields will substantially agree with the luminance levels in the other fields except the shared fields. The light level adjusting means displaces a light level adjustment range within which an amount of light representing one edge of a partial image is adjusted relative to an amount of light representing the other edge thereof. The adjusting method comprises an outputting step, a detecting step, a calculating step, and a control step. At the outputting step, the image displayed on the screen of the multi-display device is picked up in order to produce an image signal. At the detecting step, a luminance signal is sampled from the image signal in order to detect the sizes of the shared fields and the luminance levels in the shared fields. At the calculating step, a magnitude of displacement by which the light level adjusting means included in the multi-display device should displace the light level adjustment range is calculated based on the detected information of the sizes of the shared fields and luminance levels therein. At the control step, control is extended so that the light level adjusting means can displace the light level adjustment range by the magnitude of displacement.
These objects and advantages of the present invention will become further apparent from the following detailed explanation.